Caracterización fisicoquímica de la endo-quitosanasa nativa de Aspergillus kawachii y estudio de la expresión del gen (CSN)


Facultad de Ciencias Químicas

QFB. Carlos Neftali Abigail Cano González

Abstract: Aspergillus kawachii is a fungus capable of producing constituent chitosanases. Bio-synthesis can be of two types of chitosanase exo/endo (QuitA) and endo (QuitB). In the present study, this fungal strain was used to obtain an enzymatic extract which was carried out adjusted for pH of the medium to 3.5 and 8.0 for the desorption of the protein on the biomass. The concentration and purification process were by ultrafiltration after lyophilization concentrating 81x. The enzymes were purified by gel filtration chromatography and ion exchange (DEAE and SP). The physicochemical characterization of QuitA and QuitB was carried out SDS-PAGE determining the MW 26.84 and 109.0 kDa and for the optimum pH it was 5.0 and 3.0 (acid-stable activity) respectively. The metallic ion effect Hg +2 and Mn+2 significantly inhibit the activity of both enzymes greater than 70%. Cu+2 increases the enzymatic activity of the enzyme QuitA and QuitB to 132% and 136% respectively. For the determination of the hydrolysates by the enzymes, gel filtration chromatography was performed on the column sephacryl P-2 and HPAC-PAD confirming the presence of Chitosan hydrolysates of a more specific range of the degree of polymerization (DP) for the enzyme QuitB and a wide range of the DP as well as monomers for the enzyme QuitA.

Thesis Carlos Cano González